This invention relates to a method and apparatus for transmitting a document from a source location to one or more remote locations, such as by electronic mail, and more particularly, to such a method and apparatus which interfaces a printer or other display device disposed at the remote location with the document generating source irrespective of the operating characteristics and/or manufacturer of the source and display device.
Documents such as letters, reports, memoranda, legal papers, and the like, often must be delivered quickly from an originator thereof to one or more recipients at remote locations. A messenger service may be employed to hand-deliver original documents within a matter of hours; but such messenger service typically requires twelve hours or more to transport an original document over any substantial distance, such as from one major city to another. Alternatively, the text of a document, or the graphical information thereon, may be electronically transmitted from a local site to a remote site by means of facsimile transmission. However, the delivered document generally is of inferior quality and, if to be included in a formal presentation, the facsimile-received document generally must be re-typed. The aforementioned difficulties in messenger service and facsimile transmission of documents is compounded if a single document is to be transmitted to several locations.
Recently, the use of word processor systems and specially programmed computer systems for generating, storing and printing documents has been enthusiastically adopted. In these systems, digital data signals representing text may be stored on a suitable storage medium, such as a magnetic disk, from which the text subsequently may be played back and printed several times. Several manufacturers now manufacture and sell word processor and computer systems for this purpose. Some of these systems offer optional features by which a document which originates at one site may be transmitted and printed at a remote site, provided that the equipment at both sites are the same or are at least manufactured by the same manufacturer. Typically, such word processor or computer systems are provided with a so-called telecommunications output terminal to which suitable transmission and reception equipment are connected in order to transmit and receive data files associated with respective documents. In particular, an entire "document file" which normally is produced when generating a document at a word processor, is transmitted from the local site, or source, to the remote site whereat the document file is received, stored (as on a magnetic disk) and then used to print out the generated document.
A significant drawback of the aforementioned telecommunications technique for transmitting document files from one location to another is the general requirement that the display device or printer at the remote location be fully compatible with the document generating equipment. Typically, the apparatus at the remote location must be from the very same manufacturer as the apparatus at the originating location. Unfortunately, as often happens, the equipment purchased for use at one office location, such as the aforementioned remote location, may differ from the equipment purchased for use at another office location, i.e. the originating location. Consequently, interoffice telecommunication of documents often is not easily accomplished.
Although the problem of printing a document on one of various different types of print mechanisms has been recognized, as in the IBM Technical Disclosure Bulletin by Hays et al., Volume 522, No. 1 (June 1979, page 269), which describes the use of a printer adapter, this Technical Disclosure Bulletin apparently requires that the printer and document generator operate in accordance with the same format. That is, the entire document file is transmitted to and utilized by the adapter. However, there is no suggestion in this Technical Disclosure Bulletin of locating the printer at a remote site and the text generator at a local site.
Although some word processor and computer systems can be utilized with printers and display devices furnished by other manufacturers, suitable interfacing therebetween is necessary for interaction between the text generating equipment and the printing or display equipment. In some instances, signals might be returned from the printer mechanism to the text generator for proper operation of both devices. However, in view of the large numbers and variety of word processors and computer systems, the requisite document transmission interfacing between any one of such systems and any one of the various printers and display devices with which those systems can be used would result in an almost impossible task to attain universal compatibility.
The present invention proceeds on the recognition that, rather than transmitting a complete document file from a text generator to a printer, all that is needed to achieve printing at a remote location is the transmission of printer commands. It has been found that, although there are a large variety of word processor and computer systems, most printers that are usable therewith require the same general printer commands in order to operate satisfactorily. At the present time, many word processor and computer systems are provided with printer output terminals whereat only information necessary to control the printer, such as the printer commands, are provided but the remainder of the document file is not. For example, word processor/printer interfaces and computer/printer interfaces may be of the RS232 specification or other specifications such as RS232-C, Centronics Parallel, Qume 13-bit parallel, Diablo 12-bit parallel, Current Loop, and IEEE 488. As is described in greater detail below, the printer commands provided at the printer output terminal at a local site are utilized by the present invention to drive most commercial printers, such as those provided with printwheels, at a remote site.